Acoustic device



July .2, 1929. D. M. MEULLER 1,719,437

' ACOUSTIC DEVICE I Filed June 4, 1926 F131. 1 n Fi .2 /4 /9 /J 23 /4 /5 INVENTOR Dixon M. Meuller ATTORNEYS Patented July 2, 1929.

UNITED STATES DIXON M. MEULLER, OF PORT WASHINGTON, NEW YORK.

ACOUSTIC DEVICE.

Application filed June 4,1926. Serial No. 113,729.

This invention relates to means for rendering audible the vibrations produced by the vibrating mechanism of a sound-reproducing apparatus such as a radio receiving set, or a phonograph, and the main object of the invention is to improvethe tone and render it pure and true to the original or transmitted tone both in pitch and timbre.

A further object of the invention is to provide, for a radio receiving set, an extremely compact and highly efficient acoustic device which presents a neat, attractive appearance.

Other objects will appear hereinafter.

In the drawings: J

Fig. 1 is a vertical sectional view of the device;

Fig. 2 a side view thereof; and

Fig. 3 a top plan view.

In its present form the invention is embodied in a table lamp and is adapted form a part of a radio receiving set. It 1s, however, susceptible of many other adaptations.

Referring to the parts by numerals, 1 represents the base of the combined lamp and acoustic device. The base 1 is centrally formed with an upwardly extending socket portion 2 formed with a central bore to receive the'electrical conduits. Mounted upon the upper end of the central portion 2 is a vertically disposed electric lamp socket member 3, which is held to the portion 2 by a tubular connecting member 4. This connecting member 4 is threaded into the portion 2 and into the lower end of the lamp socket member. The upper end of the socket member 1s formed with the usual'threaded lamp socket in which is mounted an electric lamp bulb 5. The circuit wires 6 for the lamp lead from the socket member 3. downwardly through the connecting member 4 and the base 1 and terminate in a plug 7, whereby the lamp may be connected into a source of current.

Rigidly supported, as at 8, by the lamp socket 3 are a plurality of upwardly extending arms 9. These arms form a support for an electrically operated vibrating unit 10. This unit is of a standardform used in connection with radioreceiving'sets and it is thought that a detailed shdwing and description of it is unnecessary in the present case,

The electric current for operating the unit 10 is'led to it bya pair of wires 11 which extend downwardly from the unit into the lower end of socket member 3, through the connecting member 4 and out through the under side ofthe base alongside the wires 6. The outer ends of the wires 11 terminate in plugs 12 which are adapted to be connected to a radio receivin set. A slender rod or post 13 forms part of the vibrator unit and extends .upwardly for a material distance above the body of the unit. This post is vibrazed by the vibrator mechanism of the um An acoustic member 14 in the form of a lamp shade is mounted upon the post 13. The upper end of this member is in the form of a conical diaphragm 15. In plan, this diaphragm )8 oval or elliptical as shown in Fig. 3. At ts center the diaphragm is apertured to receive a plug 16 formed with an outwardly extending conical flange 17 which bears against the upper face of the diaphragm.

' Threaded upon the lower end of the plug 16 is a nut 18. Interposed between the nut 18 and the under face of the diaphragm is a conical washer 19 which is forced against the diaphragm when the nut is tightened. This holds the plug 16 firmly to the diaphragm. The plug is formed with a vertical bore to receive the vibrating post 13 and a set screw 20 is threaded transversely into said bore adjacent the upper end of the plug to bind the plug to the post 13. Secured to the diaphragm 15 entirely around the peripheral edge thereof is a skirt 21. This skirt extends straight down from the diaphragm to a point ad acent the lower end of the lamp socket 3. The diaphragm and skirt thus formi a hood-like shade which covers and conceals the vibrator unit 10, the lamp 5.and the socket 3.

The diaphragm 15. is formed of comparatively stiff pasteboard, parchment, or an imitation thereof. The skirt 21 is preferably formed of parchment or an imitation thereof materially less stifl' than the diaphragm. To preserve the form of the lower end of the skirt an oval or elliptical ring 22 is secured within it in any suitable manner. At its upper end the skirt is glued or pasted to an upturned flange 23 formed around the peripheral edge of the diaphragm.

When the plugs 12 are connected to a re ceiving set and the vibrator unit is operated by the impulses received through the wires 11 the post 13 will be vibrated. The shade 14 is rigidly secured to the post 13 by the set screw 20 and the entire shade is supported solely by said post. When the post is Vibrat/ed, therefore, the shade is directly vibrated by and with the post, the shade being free at all other points. By forming the acoustic member or shade as shown and described, in actual practice, most excellent results have been attained. The tones reproduced are of unequaled purity and show an almost perfect fidelity to the original or transmitted tones both in trueness of pitch and naturalness of timbre. The objectionable megaphonic quality of tone usually present in radio acoustic devices is unnoticeable in the present invention. A material factor in the production of the pure tone is the shielding or bafiiing effect of the skirt 21 which extends fora material distance below the diaphragm and prevents the sound waves propagated from the opposite faces of the diaphragm fromintermingling and interfering with each other. While the skirt prevents this objectionable interference it does not 0 struct the propagation of the waves straig t downward from the under face of the'diaphragm. The opening defined by the lower free end of the skirt has an area subs'tantially as great as the'projected area of the diaphragm, and the cross sectional dimensions of the skirt are uniform throughout its depth. The material of which the skirt is constructed is also such as to prevent its imposing objectionable resonant impurities upon the'tone given forth.

The acoustic member 14 is very compact in comparison with radio cone speakers ofstandard form. Excellent results are obtainable by the use of an acoustic member of the present form having an elliptical diaphragm Whose major and minor axes measure only eight and five inches respectively, and having a skirt eight or nine inches in length. An

.acoustic member having these dimensions is to give more satisfactory results than a circu lar one. The elliptical diaphragm and the skirt 21 represent a most desirable combination in an acoustic device. The term diaphragm is used in its broadest sense and is intended to include any suitable wall-like member capable of being moved by the vi brating mechanism to-produce the sound.

What I claim is:

1. A device of the class set forth comprising a vibrating mechanism including an upwardly extending vibrating post; a borizontally disposed stiff diaphragm rigidly con nected atits center tosaid vibrating post and entirely sup "orted thereby; and a skirt of parchment like material carried by the diaphragm and extending from the periphery thereof downwardly for a material distance, theopening defined by the lower end of said skirt having substantially as great an area as the projected area of the diaphragm and being in direct alinement with the diaphragm.

2. A device of the class set forth comprising a vibrating mechanism including a v-ibrating post; a horizontally disposed stiff diaphragm operatively connected to said vibrating post; and a skirt carried by the diaphragm and extending from the periphery thereof downwardly for a material distance, the opening defined by the lower end of said skirt being in direct alinement with the diaphragm and having an area substantially as great as the projected area of the diaphragm.

3. A device of the class set forth comprising a vibrating mechanism including a vibrating post; a conical diaphragm operatively connected at its center to said post, said diaphragm being of oval form in plan; and a skirt of parchment-like stiffness extending from the periphery of the diaphragm fora material distance, the opening defined by the free end of said skirt beingin direct alinement with the diaphragm and having an area substantially as great as the projected area of the diaphragm.

4:. An acoustic device comprising a conical diaphragm of oval form in plan adapted to be connected at its center to a vibrating element; and shield means arranged at the pe riphery of the diaphragm and adapted to prevent interference between sound waves leaving the opposite faces of the diaphragm, said shield means being formed and arranged to leave the areas of the opposite faces of the diaphragm freely exposed in the direction of the cone axis and avoid the obstruction of sound Waves propagated in an axial direction from either face.

5. An acoustic device comprising 9. dia-' phragm adapted to be connected to a vibrating element; and non-resistant shield means arranged'at the periphery of the diaphragm to move therewith and adapted to prevent 1nterference between sound Waves leaving the opposite faces of the diaphragm, said shield means being formed and arranged to leave the areas of the opposite faces of the dia phragm freely exposed.

6. An acoustic device comprising a relatively stifl diaphragm adapted to be connected .to a vibrating element, and a skirt of less stifi'ness than the diaphragm extending from the periphery of the diaphragm a material distance from one face thereof.

7. A device of the class set forth comprisinga vibrating mechanism including a vibrating post; a diaphragm rigidly connected at its center to said post; and shield means carried by the diaphra m adapted to prevent interference between the sound waves leavextending from the periphery thereof downwardly for a material distance around the vibratin mechanism the o enin defined D 2:!

; by the lower end of said skirt being in direct alinement with the diaphragm and having an area substantially as great as the projected area of the diaphragm; and a portable supporting standard for the vibrating mechanisin provided with a base and adapted to hold the device upright with the skirt elevated.

-9. An acoustic device comprising a diaphragm; and an annular shield extending around the periphery of the diaphragm and for a material distance from one face thereof, said shield being non-resonant and open at its outer end.

10. An acoustic device comprising a diaphragm adaptedto be bodily freely vibrated; and an annular shield extending around the periphery of the diaphragm and for a material distance from one face thereof, said shield being non-resonant and open at its outer end and the area of the opening being substantially as great as the projected plan of the diaphragm.

11. An acoustic device comprising a diaphragm adapted to be bodily freely vibrated; and an annular shield extendingaround the periphery of the diaphragm and for a material distance from one face thereof, said shield being non-resonant, open at its outer end, and at all points in its length being substantially of the same cross-sectional contour as the projected plan of the diaphragm.

12. An acoustic device comprising a diaphragm adapted to be bodily freely vibrated;

and an annular shield-extending around the periphery of the diaphragm and for a mate rial distance from one face thereof and carried thereby, said shield being non-resonant and open at its outer end andthe area of the opening being as great as the projected plan of the diaphragi 13. An acoustic device comprising a diaphragm adapted to be bodily freely vibrated; and an annular shield extending around the periphery of the diaphragm and for a material distance from one face thereof and carried thereby, said shield being non-resonant, open at its outer end, and at all points in its length being substantially of the same crosssectional contour as the projected plan of the diaphragm.

14. An acoustic device comprising a relatively stifl' conical diaphragm adapted to be connected to a vibrating element; and a skirt of less stiffness than the diaphragm, carried by the diaphragm and extending around the periphery thereof and away from the cone apex.

15. An acoustic device comprising a conical diaphragm adapted to be connected to a vibrating element; and a skirt carried by the diaphragm, extending around the periphery thereof and in a direction away from the cone apex, said skirt being non-resonant.

16. An acoustic device comprising a diaphra m adapted to be connected to a vibrating element; and non-resonant sound-directing means extending around the periphery of said diaphragm and for a material distance,

from one face thereof and being open at its outer end and formed and arranged to permit a free, unobstructed propagationof sound Waves outwardly in one direction from substantially the entire area of the'diaphragm.

17. An acoustic device comprising a diaphragm adapted to be connected to a vibrating element; and non-resonant sound-directing means extending around the periphery of-said diaphragm and for a material distance from one face thereof and formed and arranged to permit a propagation of sound Waves outwardly through the air in one direction from substantially the entire area of said diaphragm face and to prevent interference between Waves leaving said face and those leaving the opposite face of the diaphragm.

In testimony whereof I hereunto affix my signature.

DIXON M. MEULLER. 

